The present invention relates to a roofing slab having a vent opening which is arranged in the central region, is limited by a peripheral edge collar and is extended over in hood-like manner by a cover and with which there is associated a hose connecting pipe directed towards the bottom side of the roofing slab.
A roofing slab of this type is known from Federal Republic of Germany OS No. 26 59 788. The collar over which the cover extends is edge-locked in the vent opening cut out of the roofing slab which is formed by a tile, detent projections engaging below the bottom of the edge of the opening. The hose connecting pipe which is introduced from the bottom is associated in the same manner except that it grips over the top edge of the vent opening by corresponding detent means. This development is still too difficult in manufacture for an article of mass consumption. The detent evasion movement extends into the support walls. One is thereby limited to certain materials and in any event to ones which return completely into their position.